The pull-up is one of the best exercises in existence. It is a full body movement that requires not only upper-body strength but also core control and appropriate mobility. For athletes, or anyone else who wants to maximize sports performance, the Pull-Up should be a staple in your program. Along with the deadlift, it is probably the best single exercise (if there is such a thing) that teaches you to tie the trunk to the arms, and integrate your core and upper extremities.
Unfortunately, most men and women are unable to do pull ups. Even among those who can, most can't do a REAL pull up, but rather a shortened range, poor technique, grunting and screaming (sometimes literally) mediocre form of a pull-up. Don't get me wrong, I applaud you if you can manage to get your chin above the bar, regardless of the technique, because it still puts you ahead of 99% of the population. However, literally everyone should be able to do at least a single, clean technique, chest-to-bar pull up. Yes, CHEST to bar. Not chin to bar.
The good news is that you can get there, no matter where you start from.